A prod event surfaced today with `start_dt=2026-05-01T12:00Z` and
`end_dt=2026-03-30T12:00Z` — end was 32 days BEFORE start, almost
certainly from an earlier tool-call mishap (Fable #161). The
list_events filter trusted the bogus end_dt and excluded the event
from every read path that hit the upcoming window, even though
start_dt was correctly in range. The event stayed visible in the
calendar grid (different range) but vanished from "Upcoming",
search, briefings, and journal prep events list.
This is the hotfix half of the response. The structural follow-up is
Fable #160 — replace end_dt with a duration column so invalid state
becomes inexpressible.
## A. Filter robustness in list_events
Treat `end_dt <= start_dt` as if no end_dt exists. The filter now
splits into two branches:
- valid duration: end_dt IS NOT NULL AND end_dt > start_dt AND
end_dt >= date_from
- no/invalid duration: (end_dt IS NULL OR end_dt <= start_dt) AND
start_dt >= date_from
Same change applied to the recurring-event expansion's `duration`
calculation, which was producing negative timedeltas for corrupted
rows and computing nonsensical occurrence end times.
## B. Write-side validation in create/update
`create_event` and `update_event` now raise ValueError when the
resulting state would have end_dt <= start_dt. Update validates
against the *post-update* state, not just the field being changed —
so pushing start_dt past an existing end_dt also fails loudly. Bad
data shouldn't be persistable from any write path.
Surfaced cleanly:
- Calendar tool wrappers (create_event_tool / update_event_tool)
catch ValueError and return `{success: false, error: ...}`, which
the model can read and self-correct.
- Route handlers (POST /api/events, PATCH /api/events/<id>) catch
and return HTTP 400 with the validator's message instead of
letting it bubble to a 500.
4 new tests in test_events_service.py:
- create rejects end before start
- create rejects equal start/end (zero duration)
- update validates the post-update state (start pushed past existing end)
- list_events surfaces an event whose end_dt is before its start_dt
34 event-related tests pass; ruff clean.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
bvandeusen
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